as stated here, the sessions kPlugin should remember the arrangement of tabs and windows effective at the time of exiting.
That would imply refreshing the list the Plugin wrote to "prefs.js", to delete the lines referring to Ts&Ws having been closed since the last opening or reloading action.

Cheers
SoerenB

KM 1.74b4u1 in Wine 1.6 on Linux Mint 17 (XFCE)
- and still being surprised every day
how easily all of this works ...